How best to record class lectures

October 4, 2013 11:42 PM

How can I record my class lectures so they are not painful to hear when replayed?

I like to record my class lectures because I have trouble concentrating, and need to hear them a second time. The recorders I've used in the past all record a lot of extra noise, and the professor's voice also does not come through that well. I always sit only about 5 feet away from the professor. Is there any way I can fix this so that replaying the lectures doesn't cause so much strain and give me a headache? I'm not at all technologically inclined so I don't know if there's an easy solution to this?

Someone mentioned a directional microphone but I don't really understand the uses of one, and if it would apply in this case? Would getting a more expensive recorder help? On Amazon there are ones for $25 and ones for $60. There's also one with a "noise cancel" button. What is this and does it actually work? Can I do anything to the recordings after they've been recorded to improve the quality? Thanks for any advice.

posted by Blitz to Computers & Internet (10 answers total)

Yes, a directional microphone would help. You would use it by pointing it at your professor. It will pick up more sound from the direction it's pointed, and less from other directions.

"Noise cancel" features can be good at cancelling constant noise (like static, humming, buzzing, or white noise) but often don't do anything for noise that is intermittent (like people talking or moving). Some recorders may have multiple directional microphones, and the ability to remove sounds (even intermittent ones) that come from a different direction than the main mic.

For constant noise, you can also try using a program like Audacity that has a noise removal tool.
posted by mbrubeck at 11:57 PM on October 4, 2013

One thing I've discovered about small digital recorders is that they pick up a lot of noise by direct transmission. So like if the recorder is sitting directly on a tabletop, then picking something up off the table, or tapping on the table, will make a Very Loud Noise on the recording. If that's part of the problem you're having, you might try getting a tripod to set it on. But yeah, a directional mic will also help for sure.
posted by Now there are two. There are two _______. at 12:14 AM on October 5, 2013

Response by poster: Oh, the directional mic sounds like a good idea but now I'm confused. Is it something I have to buy separately from the recorder or can I find a recorder that has one included? Are they big and bulky? I want it to be somewhat discreet that I'm recording since I sit at a seminar style table. Thanks.
posted by Blitz at 12:24 AM on October 5, 2013

There are multiple cans of worms here, and equipment sometimes exceeds expectations, but FWIW..

Noise reduction..
..comes in flavors. The type most common in handheld recorders is probably just dynamics adjustment - reducing the volume of already low parts, and boosting the highs. This works well if the background noise truly is background, and for quieting the portions of a recording where the loudest source isn't active. The NR might also act on specific frequencies, boosting typical vocal ranges and reducing others, but both of these techniques are limited, that's why location audio is done with boom mics and lavaliers.

Directional:
Your basic mic picks up sound from anywhere, but there are models that have varying levels of "directionality." The typical terms going from "anywhere!" to "right there!" are omni, cardioid, hyper-cardioid, shotgun. Cardioid would likely simply be called "directional" on consumer gear. If there's a portable voice recorder with a directional mic, I've never seen it.

Shotguns:
All mics are not created equal, and putting the word "shotgun" doesn't magically make it super-directional, so before googling, I would have said that the cheapest shotgun you'll find that really IS directional would be about $400. But it looks like technology marches on, as there are a number of discussions of <>
So if you have a recorder that accepts an external mic input, add a $25-50 shotgun mic, and a small stand, you'd seem to be pretty good to go.

If it's a seminar table, can you simply put it close to the teacher? Proximity matters more than anything. A chunk of foam with a slit in it would hold it up and reduce noise from vibration.

Note: If you're going with an external mic, make sure they work together. Cheaper equipment will have 2.5mm or 3.5mm connections, pro stuff will have XLR. Some microphones will also need power, and can get that power either from the recorder, or from a battery inside the actual mic body.
posted by Jack Karaoke at 1:06 AM on October 5, 2013 [1 favorite]

I want it to be somewhat discreet that I'm recording since I sit at a seminar style table.

If the discretion is necessary because the professor doesn't know you're recording, that's a problem.

If it's just that you don't want your equipment taking up an unsociable amount of table space, and the professor is willing to help, perhaps a wireless lapel mike that everybody could pick up if they needed to?
posted by flabdablet at 1:50 AM on October 5, 2013 [3 favorites]

Do you have a smartphone? I've seen little 3-4" directional mikes made to be used in conjunction with a recording app. Apparently they do the trick in a small lecture environment.
posted by AnOrigamiLife at 3:09 AM on October 5, 2013

Part of the reason that you can hear better in person than on the recording is that your brain uses sound cues from both ears to filter out unwanted noise. A recorder on the table can't record those cues. You might try a pair of binaural microphones (say, clipped to a pair of glasses right by your ears) and then listen back on headphones. You won't have to worry about correctly aiming a directional mic, and it should sound pretty close to what you hear in class.
posted by fogovonslack at 6:00 AM on October 5, 2013

You're going to have a really hard time getting a clean recording without spending a lot of money. Good mics, as anyone who works in film can tell you, are expensive. Cheap directional mics are generally not that good, and even a good one you'd have to get very close to your professor. Maybe you could try to use a shock mount with something like a Zoom H2, but that would be a marginal improvement. Less noise, but the voice wouldn't be picked up that clearly and any background noise, say someone talking or eating, would still get picked up.

If you could convince your professor to wear a lavalier that would be the best solution, but I can't imagine any professor agreeing to that. I think you would be best off working on your concentration, really.
posted by catwash at 10:06 AM on October 5, 2013

Professor here. I've had students ask me if they can put the recorder on the table/lectern/whatever near me, and I always say yes. You should ask the prof's permission to record anyway, so why not try it?
posted by kestrel251 at 10:44 AM on October 5, 2013 [1 favorite]

Seconding kestrel251 on both counts - students putting a recorder on my lectern is not uncommon, but you absolutely should ask permission before recording a lecture. Most lecturers will be fine, but some are very touchy about it. If you happen to be in the UK, MeMail me, since there's some specific legal issues (both good and bad for you!)
posted by firesine at 11:44 PM on October 5, 2013